The kinetics of release of fluorescent dye from liposomes due to the lytic action of peptides such as melittin and mastoparan was studied, and a method for assaying lytic compounds was developed. The method is more convenient and sensitive that hemolysis for detecting and quantitating lysis. A survey of peptides found that liposome lysis was not necessarily correlated with mast cell degranulating activity, because peptides could contain either, both, or neither of these activities. Further evaluation of National Bureau of Standards solid phase fluorescence standards was carried out, using a second generation set of standards. Current work involves measuring the corrected emission spectra of different phosphors imbedded in sintered polytetrafluoroethylene strips.